1. Field of the Invention
The present invention relates generally to reed switches and methods of use, and more specifically to mounting arrangements and configurations.
2. Description of the Related Art
Reed switches are magnetically operated switches, which are generally formed by a pair of spaced ferromagnetic contacts or blades, hermetically sealed in a glass capsule. In a typical application and use of a reed switch, the blades are connected to outside leads—each outside lead being part of a circuit. The exposure of the blades to a magnetic field—coming from either a permanent magnetic or electromagnetic generation—forces the blades to move, either contacting one another or moving away from one another. In what is known as a normally closed reed switch (“Normal” in this sense and as will be used herein means a state where the reed switch is exposed to a magnetic field), the blades touch when exposed to a magnetic field. By removing the magnetic field, the normally closed reed switch opens and the contacts will no longer touch. Contrariwise, in a normally open reed switch, the contacts touch in the absence of a magnet. By exposing the normally open reed switch to the magnetic field, the contacts move apart and the circuit is opened. After the magnetic field has been removed from these reed switches, the blades will return to their original position.
Reed switches have been used in everything from computers and copying machines to automobiles and security systems. The general concept applied in the majority of these devices is the ability to activate a switch (that is, causing the ferromagnetic blade to move, be it closing the circuit or opening the circuit) via the use of a magnetic field. The activating of these switches allows communication to be established with systems or devices. In some instances the communication may be the lack of a signal or electrical energy being returned when the switch opens the circuit, while in other instances, the communication may be the circuit being completed. Examples include using a reed switch to automatically communicate with lights, air conditioning systems, power controlled devices and the like. As a specific use in security systems, reed switches have been used to monitor the “change of state” of something. For example, a reed switch can cause a circuit to be completed or broken when a window or door opens or closes. This change of condition (opening or closing of the circuit) can automatically be detected by a central alarm system or the like, indicating whether or not an unauthorized “change of state” has occurred. A typical security use of such a reed switch may be, for example, on a window or door of a house or on a roll-up door of a storage shed.
With the use of reed switches, several design considerations must be taken into account. Reed switches are by their very nature fragile—that is, the glass capsules can break. An exacerbation of their fragile nature is likelihood that forces may be imparted thereon. Therefore, in the design and installation of reed switches, the general trend is to place the reed switches in various locations that will not experience an impact or force. For example, on roll-up doors, the placement of reed switches (generally alarming the door) in these various locations (e.g., floor, door track, latch) has lead to an inconsistent placement of the reed switches. Additionally, many door manufacturers will not and have not provided a consistent location on their doors for the placement of a reed switch.
There have been various attempts by alarm installers to come up with a way to attach a reed switch and magnet to a roll-up door that will not degrade the normal functionality of the door. The prominent means of reed switch and magnet attachment has been drilling holes into the door facing (door track) and door curtain—then attaching screws. However, the door manufacturers did not design their doors for additional holes or screws (pop-rivets, bolts, etc.) to attach a reed switch. As such, side-effects of these invasive modifications to the door facing and door curtain have included a compromise to the normal opening and closing operation of the door and a greatly diminished cosmetic appeal of the door facing. The only other option of reed switch attachment has been with clamping devices that clamp to the roll-up door facing. With such an option, the magnet is also lined up adjacent to the clamping reed switch holder and screwed to the roll-up door curtain. However, clamping reed switch devices almost always move, get misaligned with the magnet, or completely fall off the door. The magnet is also very invasive to the door curtain and dangerous because of the sharp screws protruding through the door curtain.
Typically, the roll-up door is installed by the door installers. Then, the alarm company installs the reed switch. The roll-up door installer routinely returns to the job to repair the door after the alarm installer has installed the reed switch. Oftentimes, the door installers have to cut protruding reed switch mounting screws in an effort to obtain the normal function of the roll-up door. Alternatively, they have to readjust the door to attempt to get around the problems that the attachment of the reed switch imposed on the normal opening and closing operation of the door.